Device for sheets conveyance

ABSTRACT

The sheets conveyance device, used in a converting press for paper or cardboard sheets comprising at least one feeding station, a converting station, a waste stripping station and a delivery station for converted sheets, comprises two endless gripper bar chains ( 5, 6 ) assembled for conveying the sheets from the feeding station to the delivery station, a transverse driving shaft ( 2 ) equipped with driving wheels ( 3, 3′ ) of the endless gripper bar chains ( 5, 6 ) and at least one device for sheets capture secured to the endless gripper bar chains ( 5, 6 ). The transverse driving shaft ( 2 ) is separately driven from the other press stations by at least one independent motor/reductor ( 1 ). The independent motor/reductor ( 1 ) is able to function by driving cycles including at least one motion phase and one deceleration and/or breaking phase controlled by a control device (CDE), each independent motor driving cycle duration being equivalent to a converting cycle duration of said converting station.

[0001] The present invention relates to a device for sheets conveyance, into a converting press for paper or cardboard sheets comprising at least one feeding station, a converting station, a waste stripping station and a delivery station for converted sheets, said conveyance device including two endless gripper bar chains assembled for conveying the sheets from the feeding station to the delivery station, a transverse driving shaft equipped with driving wheels for the endless gripper bar chains and at least one device for sheets capture secured to the endless gripper bar chains.

[0002] The wording “transverse” means here an horizontal direction, perpendicular to the machine axis.

[0003] Concerning known converting presses, only one electric motor usually drives the whole machine. This motor directly actuates an inertia flywheels, a clutch brake device being inserted between this flywheels and the other machine bodies. This system drives all elements functioning with synchronism, in particular the movable beam of the platen press, the waste stripping and blank delivering stations, as well as the chains bearing the gripper bars ensuring sheets capture and conveyance from one station to the next one.

[0004] A sheets conveying and converting cycle includes a sheets stop phase during which it is proceeded to a converting operation, such as blanking or waste stripping, and at least one moving phase during which the sheet is conveyed from a station to the next one. This moving phase necessarily includes an acceleration and a deceleration phase and, usually, between both, a phase during which the sheet slightly moves at a constant speed.

[0005] Various embodiments carrying out this kind of cycle were already pointed out, in which the wheels driving the chains are interdependent in rotation with a coupling unit which is, by axial displacement, alternatively caught or released from a driving unit, while standby means release or immobilize the wheels driving the chains, although the driving unit is alternatively driven in one or another rotative direction.

[0006] Such mechanical devices were described for example with patents CH 219422 and CH 411555. For such devices, an oscillating toothed segment operating onto the transverse driving shaft of the gripper bar chains via a pinion is actuated by a rod connected to an eccentric secured on the top of a shaft driven by the general machine driving device, which carries out a complete rotation by a back and forth run of the oscillating toothed segment.

[0007] In relation with this kind of mechanical drive, one deals with a single motion law, determined by the parts geometry. This kind of driving device is very suitable to low or average rates up to approximately 5'000-6'000 sheets/hour; beyond, accelerations and decelerations at the beginning and at the end of the motion phase become very strong. However, after the sheets blanking operation, the latter are still connected only by their nicks, which can break in the case of heavy acceleration, causing a machine jam.

[0008] Several mechanical devices were proposed to overcome this defect. The patent CH 411555 suggests to place the driving of the toothed segment under the control of a double cam sending a rocking motion to a lever which, by means of a connecting rod drives the toothed segment, whereas among the two lever elements cooperating with the two cams, the one, which is sending the back free motion to the toothed segment, is elastically closed up against the cam. The cams system allows to amend the motion law by relieving the start-up, however, for a set of reference cams, this motion law cannot be amended any more, except when changing cams.

[0009] One knows also about devices in which one tried to remove the time delay needed for the blanking operation. In one of those devices, the manufacturer gave a linear motion to the two blanking station platen, so that the latter travel together with the blanked sheets, solution which allowed removing the time delay while modulating the linear displacement motion of the endless gripper bar chains.

[0010] The aim of the present invention is to deal with a device for sheets conveyance allowing high rates while ensuring at will carrying out an optimal sheets conveying cycle without any too strong accelerations which could likely break the nicks between the sheets blanks. Another aim of the invention is to allow the rate amendment of the sheets conveying cycle, independently from the conveying cycle of the converting station. The rate modification of a sheets conveying cycle deals with acting on the acceleration and deceleration curves and on the respective duration of a cycle phases according to the kind of work to carry out, without proceeding, between two works, with parts exchanges of the sheets conveyance device.

[0011] These aims are reached by a sheets conveyance device, into a converting press for paper or cardboard sheets comprising at least one feeding station, a converting station, a waste stripping station and a delivery station for converted sheets, said conveyance device including two endless gripper bar chains arranged for conveying the sheets from the feeding station to the delivery station, a transverse driving shaft equipped with driving wheels for the endless gripper bar chains and at least one device for sheets capture secured to the endless gripper bar chains, device for sheets conveyance in which said transversal driving shaft is separately driven from the other press stations, by at least one independent motor, said independent motor being able to function with driving cycles comprising at least one motion phase and one phase of deceleration and/or stops controlled by a control device, the duration of each independent motor driving cycle being equivalent to the duration of a converting cycle of said converting station.

[0012] The driving of the sheets conveyance device by an independent motor instead of driving it by the same motor than the other converting press stations was wrong prejudged, one fears namely a synchronization defect between the sequential sheets run and the blanking platen operation of the downstream stations. The inventors noted at the contrary that an order, particularly an electronic order, which receives a representative signal of the blanking station platen location and a representative signal of the gripper bar chains location allows to control the independent motor driving the gripper bar chains run with optimal synchronism related to the platen cycle. During a conveying cycle, a control device driving the independent motor by delivering a suitable electrical current is able to adjust with much more flexibility than a mechanical device could do it, the characteristics of the acceleration phase, of the deceleration phase and of the breaking phase of the conveying device. The conveying by means of the independent motor allows in particular to better adjust the relative duration of the moving and breaking phases of the gripper bar chains with the moving and breaking phases of the diecutting platen and, consequently, to decrease the duration of the platen breaking phase, which allows increasing the whole machine production rate.

[0013] Other characteristics and advantages will be apparent to one skilled in the art from the description of an embodiment of the invention, with reference to the drawing, which shows, respectively a side view and a top view of:

[0014]FIGS. 1a and 1 b for the establishment of a driving motor of a conveyance device into a converting press;

[0015]FIG. 2 is a diagrammatic view of the control device of this motor;

[0016]FIG. 3 shows the recording of a cycle characteristics.

[0017]FIGS. 1a and 1 b show an independent motor/reductor unit 1 directly assembled with a lengthening of the transverse driving shaft 2 which comprises the driving wheels 3, 3′ of the endless gripper bar chains 5, 6 of a converting press. As one notes on FIG. 1a, the motor is located at the unit 4 level, which, into a prior art converting press, comprised the driving mechanism parts of the gripper bar chains 5, 6 and the coupling parts to the motor actuating the various press stations, parts which are removed here. This independent motor/reductor 1 can thus be assembled without modifying the embodiment of an existing machine. For one skilled in the art it will be obvious that the motor can also be secured in a position so called “in mirror”, i.e. on the opposite end of the transverse driving shaft of the gripper bar chains, therefore as well in a position so called “operator's side” OS than in a position so called “opposite operator's side” OOS. The independent motor/reductor 1 can also be mounted in a position between frames 7, 8 and actuate the transverse shaft 2 by known means such as pinions, belts, chains, which allows to remove the driving side units 4 and to reduce the width dimension of the device.

[0018] The independent motor/reductor actuating the endless gripper bar chains 5, 6 is preferably an electric motor of high dynamics regulation. This independent motor/reductor 1 can be selected among the synchronous motors, asynchronous, with d.c. motor, with or without brake, commercially available. For example, at the time of the depositor's tests, a brushless synchronous driving device comprising a motor type HXA60VH distributed by ABB Normelec S.A. (Switzerland) allowed to drive the endless gripper bar chains 5, 6 of a converting press at significant rates, while removing the original mechanical driving means. Several manufacturers offer electric motors with standard embodiments able to reach couples up to 200-500 Nm, allowing to reach gripper bar chains accelerations up to 25 to 70 m/s². The cost of such standard motors is lower than the one of all mechanical elements of known devices.

[0019]FIG. 2 shows the schematic diagram of the electronic control device of the independent motor/reductor 1. The CDE control device receives from an absolute and incremental coder 9 a signal emitting the exact location of the blanking platen 10, this signal being used as a master reference within the whole system. The CDE control device also receives from an absolute and incremental coder 11 the absolute location of the gripper bar chains 5, 6; the CDE control device finally receives the angular location of the independent motor/reductor 1 scanned by the absolute and incremental coder 12. The comparison between these signals allows the electronic CDE control device to exactly define the blocking and releasing times of the independent motor/reductor 1, i.e. to define the beginning and the end of the breaking phase and to issue the current/tension feeding instructions defining, at any time, accelerations and speed rates of the independent motor/reductor 1.

[0020] The FIG. 3 shows five curve 13 to 17 on a same diagram, showing in arbitrary units, for the curve 13, the tension, for the curve 14, the intensity of the current feeding the independent motor/reductor 1, for the curve 15, the acceleration, for the curve 16, the reached speed as well as for the curve 17, the angular motion of the independent motor/reducteur 1. On this FIG. the X-coordinate axis represents the angular rotation of the independent motor/reductor 1 during one rotation, that is to say 360° which correspond to a sheet travelling from one station to the right next one.

[0021] One effectively notes on these curves the relationship between control tension and speed as well as the lack of excessive accelerations. By modifying the preset tension curve, one can easily remove the constant speed motion phase, lengthen or shorten the motion phase duration inside a cycle. 

1. Device for sheets conveyance, into a converting press for paper or cardboard sheets comprising at least one feeding station, a converting station, a waste stripping station and a delivery station for converted sheets, said conveyance device including two endless gripper bar chains (5, 6) assembled for conveying the sheets from the feeding station to the delivery station, a transverse driving shaft (2) equipped with driving wheels (3, 3′) of the endless gripper bar chains (5, 6) and at least one device for sheets capture secured to the endless gripper bar chains (5, 6) characterized by the fact that said transverse driving shaft (2) is separately driven from the other press station driving, by at least one independent motor (1), said independent motor (1) being able to function by driving cycles including at least one motion phase and one breaking phase controlled by a control device (CDE), each driving cycle duration of the independent motor (1) being equivalent to a converting cycle duration of said converting station.
 2. Conveyance device according to claim 1, characterized by the fact that said independent motor (1) is an electric motor/reductor of high dynamics regulation.
 3. Conveyance device according to claim 2, characterized by the fact that said independent motor/reductor (1) is selected among the synchronous motors, asynchronous, with D.c. current, with brake or without brake.
 4. Conveyance device according to claim 3, characterized by the fact that said independent motor/reductor (1) is assembled in the prolongation of said transverse driving shaft (2), operator's side (OS).
 5. Conveyance device according to claim 3, characterized by the fact that said independent motor/reductor (1) is secured into the prolongation of said transverse driving shaft (2), opposite operator's side (OOS).
 6. Conveyance device according to claim 3, characterized by the fact that said independent motor/reductor (1) is secured between the frames (7, 8).
 7. Conveyance device according to any of the preceding claims, characterized by the fact that it comprises an electronic control device (CDE) of the independent motor/reductor (1) able to adjust, for each driving cycle, at least durations and amplitudes of an acceleration phase, of a deceleration and of a breaking phase.
 8. Conveyance device according to claim 7, characterized by the fact that it comprises a coder (9) of the converting station location, a coder (11) of the endless gripper bar chains (5, 6) location and an angular position coder (12) of the independent motor/reductor (1), connected to said electronic control device (CDE). 